TAUVEX payload not carried by GSAT-4

Bangalore: A fateful but providential decision by the Indian Space Research Organisation (ISRO) saved a precious Indo-Israeli science payload from crashing into the sea in the failed GSLV launch mission Thursday.

Under the original plan, the ultraviolet telescope called TAUVEX was to be carried by GSAT-4, which plunged into the Bay of Bengal after the indigenously built cryogenic stage failed to fire up.

But as it turned out, for technical reasons, ISRO decided at the last minute not to include the TAUVEX and the rocket flew without it. And now the payload is safe in ISRO Satellite Centre (ISAC) in Bangalore awaiting next launch.

A collaborative experiment between the Tel Aviv University (TAU) and the Indian Institute of Astrophysics (IIAP) in Bangalore, TAUVEX aimed to image large parts of the sky in the ultraviolet band to understand how stars formed and the physics of black holes.

Under an agreement signed with the Israeli space agency in 2003, ISRO was expected to launch it as early as in 2005 but for various reasons it was getting postponed.

In 2008, a decision was taken to include it as one of the payloads of GSAT-4 but this plan was also dropped about three months before the actual launch.

"The TAUVEX payload had already been mounted on GSAT-4 and we were expecting it would be put into space by GSLV's latest mission," Jayant Murthy, of the IIAP and principal investigator of the experiment from the Indian side, told IANS.

"But the payload was stripped off in January this year and since then it has been in ISAC," he said.

If the next launch is again delayed for too long "we have to check the payload again", he said.

The TAUVEX payload, weighing about 80 kg was apparently taken off the GSAT-4 to reduce the risk to the mission due to overloading, Murthy said.

"The TAUVEX team expresses our deep regret at the failure of the GSAT-4 launch," Murthy said in a statement posted on the TAUVEX website.

"We have benefited greatly from our association with the GSAT-4 team and have the highest regard for their professionalism and ability to overcome adversity."

Similar feelings have been expressed by Murthy's Israeli counterpart Noah Brosch, director of the Wise Observatory at TAU.

"We prayed for a successful launch but instead saw the launch failure as it happened," Brosch has been quoted as saying in Space News, an international magazine published from Washington.

"As to TAUVEX, with hindsight, I am obviously relieved that it remained safely on the ground," he said and hoped that TAUVEX's launch "will take place shortly so that the Indian and Israeli astronomical communities would benefit from the data gathered by it".

While an ISRO expert panel will meet in Thiruvananthapuram Sunday to analyse the telemetry data from the ill-fated mission to pin point the cause of failure, a former ISRO scientist, who worked on cryogenic engines in the early stages of its development, says an explosion cannot be ruled out.

The Space News magazine quoting Nambi Narayanan, who formerly headed the Liquid Propulsion Systems Centre, said that explosion can occur during "hard start" - that is when a rich mixture of fuel and oxidizer is suddenly ignited in vacuum.

"While the cryoengine had been extensively tested and reviewed by experts within and outside ISRO it was not tested in conditions simulating high altitude," Narayan was quoted as saying.